This patch changes the behavior of rmdir(2) to allow it to delete
an empty subvolume by default, unless it is not a default subvolume
and send is not in progress.
New function btrfs_delete_subvolume() is almost equal to the second half
of btrfs_ioctl_snap_destroy(). This function requires inode_lock for both
@dir and inode of @dentry. For rmdir(2) it is already acquired in vfs
layer before calling btrfs_rmdir().
Note that while a non-privileged user cannot delete a read-only subvolume
by "btrfs subvolume delete" when user_subvol_rm_allowd mount option is
enabled, rmdir(2) can delete an empty read-only subvolume.
(However, rm -r cannot use for read-only subvolume containing files.)
Signed-off-by: Tomohiro Misono <misono.tomoh...@jp.fujitsu.com>
---
fs/btrfs/inode.c | 143 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 142 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index db66fa4fede6..b778776eee8e 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4387,6 +4387,147 @@ noinline int may_destroy_subvol(struct btrfs_root *root)
return ret;
}
+static int btrfs_delete_subvolume(struct inode *dir, struct dentry *dentry)
+{
+ struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
+ struct btrfs_root *root = BTRFS_I(dir)->root;
+ struct inode *inode = d_inode(dentry);
+ struct btrfs_root *dest = BTRFS_I(inode)->root;
+ struct btrfs_trans_handle *trans;
+ struct btrfs_block_rsv block_rsv;
+ u64 root_flags;
+ u64 qgroup_reserved;
+ int ret;
+ int err;
+
+ /*
+ * Don't allow to delete a subvolume with send in progress. This is
+ * inside the i_mutex so the error handling that has to drop the bit
+ * again is not run concurrently.
+ */
+ spin_lock(&dest->root_item_lock);
+ root_flags = btrfs_root_flags(&dest->root_item);
+ if (dest->send_in_progress == 0) {
+ btrfs_set_root_flags(&dest->root_item,
+ root_flags | BTRFS_ROOT_SUBVOL_DEAD);
+ spin_unlock(&dest->root_item_lock);
+ } else {
+ spin_unlock(&dest->root_item_lock);
+ btrfs_warn(fs_info,
+ "Attempt to delete subvolume %llu during send",
+ dest->root_key.objectid);
+ err = -EPERM;
+ return err;
+ }
+
+ down_write(&fs_info->subvol_sem);
+
+ err = may_destroy_subvol(dest);
+ if (err)
+ goto out_up_write;
+
+ btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
+ /*
+ * One for dir inode, two for dir entries, two for root
+ * ref/backref.
+ */
+ err = btrfs_subvolume_reserve_metadata(root, &block_rsv,
+ 5, &qgroup_reserved, true);
+ if (err)
+ goto out_up_write;
+
+ trans = btrfs_start_transaction(root, 0);
+ if (IS_ERR(trans)) {
+ err = PTR_ERR(trans);
+ goto out_release;
+ }
+ trans->block_rsv = &block_rsv;
+ trans->bytes_reserved = block_rsv.size;
+
+ btrfs_record_snapshot_destroy(trans, BTRFS_I(dir));
+
+ ret = btrfs_unlink_subvol(trans, root, dir,
+ dest->root_key.objectid,
+ dentry->d_name.name,
+ dentry->d_name.len);
+ if (ret) {
+ err = ret;
+ btrfs_abort_transaction(trans, ret);
+ goto out_end_trans;
+ }
+
+ btrfs_record_root_in_trans(trans, dest);
+
+ memset(&dest->root_item.drop_progress, 0,
+ sizeof(dest->root_item.drop_progress));
+ dest->root_item.drop_level = 0;
+ btrfs_set_root_refs(&dest->root_item, 0);
+
+ if (!test_and_set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &dest->state)) {
+ ret = btrfs_insert_orphan_item(trans,
+ fs_info->tree_root,
+ dest->root_key.objectid);
+ if (ret) {
+ btrfs_abort_transaction(trans, ret);
+ err = ret;
+ goto out_end_trans;
+ }
+ }
+
+ ret = btrfs_uuid_tree_rem(trans, fs_info, dest->root_item.uuid,
+ BTRFS_UUID_KEY_SUBVOL,
+ dest->root_key.objectid);
+ if (ret && ret != -ENOENT) {
+ btrfs_abort_transaction(trans, ret);
+ err = ret;
+ goto out_end_trans;
+ }
+ if (!btrfs_is_empty_uuid(dest->root_item.received_uuid)) {
+ ret = btrfs_uuid_tree_rem(trans, fs_info,
+ dest->root_item.received_uuid,
+ BTRFS_UUID_KEY_RECEIVED_SUBVOL,
+ dest->root_key.objectid);
+ if (ret && ret != -ENOENT) {
+ btrfs_abort_transaction(trans, ret);
+ err = ret;
+ goto out_end_trans;
+ }
+ }
+
+out_end_trans:
+ trans->block_rsv = NULL;
+ trans->bytes_reserved = 0;
+ ret = btrfs_end_transaction(trans);
+ if (ret && !err)
+ err = ret;
+ inode->i_flags |= S_DEAD;
+out_release:
+ btrfs_subvolume_release_metadata(fs_info, &block_rsv);
+out_up_write:
+ up_write(&fs_info->subvol_sem);
+ if (err) {
+ spin_lock(&dest->root_item_lock);
+ root_flags = btrfs_root_flags(&dest->root_item);
+ btrfs_set_root_flags(&dest->root_item,
+ root_flags & ~BTRFS_ROOT_SUBVOL_DEAD);
+ spin_unlock(&dest->root_item_lock);
+ }
+
+ if (!err) {
+ d_invalidate(dentry);
+ btrfs_invalidate_inodes(dest);
+ ASSERT(dest->send_in_progress == 0);
+
+ /* the last ref */
+ if (dest->ino_cache_inode) {
+ iput(dest->ino_cache_inode);
+ dest->ino_cache_inode = NULL;
+ }
+ }
+
+ return err;
+}
+
static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
@@ -4398,7 +4539,7 @@ static int btrfs_rmdir(struct inode *dir, struct dentry
*dentry)
if (inode->i_size > BTRFS_EMPTY_DIR_SIZE)
return -ENOTEMPTY;
if (btrfs_ino(BTRFS_I(inode)) == BTRFS_FIRST_FREE_OBJECTID)
- return -EPERM;
+ return btrfs_delete_subvolume(dir, dentry);
trans = __unlink_start_trans(dir);
if (IS_ERR(trans))
--
2.14.3
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